1. Field of the Invention
The present invention relates generally to an apparatus for controlling charging power, and more particularly, to an apparatus and a method for controlling a total required power of one or more wireless power receivers during a charging of a relevant wireless power receiver.
2. Description of the Related Art
Wireless power transmission technology has recently been utilized for many electronic devices, such as electric toothbrushes, electric shavers, mobile phones, and digital cameras. Studies are also being conducted on improved wireless charging of large batteries, e.g., for electric cars and subway trains.
Wireless power transmission technologies are largely divided into a magnetic field inductive coupling scheme, an electric field capacitive coupling scheme, and a Radio Frequency (RF) radiation scheme. Among them, the inductive coupling scheme is currently the most efficient and frequently used scheme.
The inductive coupling scheme is based on the same principle of an electric transformer. In a wireless power transmission system, a primary coil and a secondary coil of an electric transformer are used in such a manner that the primary coil is separated from the secondary coil and is then installed in a wireless power transmitter unit, whereas the secondary coil is installed in a wireless power receiver unit of an electronic device.
Among inductive coupling schemes, a scheme for causing a resonance frequency of a primary coil and a secondary coil to match an operating frequency of a power source and increasing the transmission distance of wireless power transmission by increasing a Q factor of each of the primary coil and the secondary coil is defined as a resonance coupling scheme. Herein, the primary coil is referred to as a “TX resonator,” and the secondary coil is referred to as an “RX resonator,” and many studies are currently being conducted on the resonance coupling scheme.
In the wireless power transmission system, data communication is performed between a TX resonator and an RX resonator in order to efficiently transmit power. For example, authentication information between the wireless power transmitter unit and the wireless power receiver unit, information on the voltage and current of received power, and information on an abnormal state of the wireless power receiver unit, are transmitted. In relation to a band for communication, there are an in-band communication scheme using a carrier frequency band of wireless power and an out-band communication scheme (for example, 2.4 GHz Zigbee® communication) using another separate band.
As described above, there is a limit on the magnitude of wireless power that the conventional wireless power transmitter unit can supply. For example, there are various classes of the magnitude of wireless power that the conventional wireless power transmitter unit can supply, such as 5-watt, 10-watt and 20-watt classes. The wireless power transmitter unit supplies wireless power while it freely varies the magnitude of power within this limit on wireless power.
However, there are diverse types of the magnitude of power that the wireless power receiver unit requires according to devices, each including the wireless power receiver unit. Even in the case of mobile phones, there are various types of the magnitude of power, such as 2.5 watt, 3 watt and 4 watt. Tablet Personal Computers (PCs) or laptop computers require more power than mobile phones, while some devices require less power than mobile phones.
When one or more devices intend to simultaneously receive power from one wireless power transmitter unit, it is common that the magnitude of total power that one or more devices require exceeds a limit on a transmitter output of the wireless power transmitter unit. Accordingly, there is a problem in that the wireless power transmission can be interrupted.
As such, there is an inconvenience in that some wireless power receiver units can receive wireless power, whereas other wireless power receiver units may not receive wireless power.